基于DES/FW-H方法的共轴刚性旋翼气动噪声预测方法及机理研究

共轴刚性旋翼高速直升机具有优良的气动性能和机动性能，是当前世界直升机领域的研究热点。与单旋翼相比，共轴刚性旋翼存在更复杂的噪声问题，如非定常气动干扰引起的高频载荷噪声、双旋翼周期相遇诱发的脉冲噪声、强干扰下的高速脉冲噪声等。本项目针对其噪声研究所面临的流场干扰复杂、配平难度大、噪声形成机理复杂等难点问题，建立适用于共轴刚性旋翼气动干扰流场的分离涡模拟（DES）方法，提高旋翼湍流尾迹模拟精度。通过将CFD方法与高效气动模型进行耦合，在保证精度的同时，显著提升配平效率。改进Farassat1噪声计算公式，避开时间导数的求解，提升高频载荷噪声预测精度。结合FW-Hpds方法构建一套高精度的共轴刚性旋翼气动噪声预测模型。针对干扰状态下的旋转噪声和高速脉冲噪声开展研究。阐明双旋翼声源叠加效应，摸清其复杂气动干扰和升力偏置所对应的特殊噪声形成机理，为我国新一代高速直升机的降噪设计提供技术支撑。

Rigid coaxial rotor high-speed helicopter has excellent aerodynamic performance and maneuverability, which is one of the research hotspot in the field of rotorcraft. Compared with conventional single rotor, there are more complex noise problems for coaxial rigid rotor, such as the high frequency load noise caused by unsteady aerodynamic interactions, impulse noise induced by periodic meeting of rotors, and the high-speed impulse noise under intense interactions. This project is aimed at the key problems in the research of its noise, such as the complexity of aerodynamic interactions, the difficulty of trim, the complexity of noise formation mechanism and so on. To improve the accuracy of rotor turbulent wake, detached eddy simulation (DES) method is established, which is adapted to the flow field characteristics of interactions. By coupling the CFD method with high efficiency aerodynamic model, the trim efficiency can be significantly improved, while the trim accuracy is ensured. To improve the simulation accuracy of the high-frequency load noise, the Farassat1 formula is improved for noise calculation to avoid the solution of time derivative term. Then, a robust and accurate prediction model of rigid coaxial rotor aerodynamic noise is established, combined with FW-Hpds method. The rotating noise and high-speed impulse noise in interaction states are studied. The superposition effect of the sound sources of rotors is clarified. The formation mechanism of noise corresponding to its complex aerodynamic interactions and lift offset characteristics are revealed, which will provide technical support for the noise reduction design of the new generation high-speed helicopter.